Manufacture of hydrogen

ABSTRACT

A process for the manufacture of hydrogen which comprises contacting tungsten dioxide (WO2) with steam at a temperature below about 700*C., preferably between about 400* to 650*C. to produce hydrogen product and W4O11 and regenerating the WO2 from the W4O11 with a reducing gas at a temperature between about 725*C. and about 775*C.

United States Patent [191 Seitzer Jan. 7, 1975 MANUFACTURE OF HYDROGEN [75] Inventor: Walter H. Seitzer, West Chester, Pa.

[73] Assignee: Sun Ventures, Inc., St. Davids, Pa.

[22] Filed: Mar. 7, 1974 [21]. Appl. N0.: 448,847

[52] US. Cl. 423/657, 423/648 [51] Int. Cl. C0lg 41/00, COlb 1/02, COlb l/03 [58] Field of Search. 423/657, 648, 606

{56] References Cited UNITED STATES PATENTS 4/1912 Arsen. 423/606 OTHER PUBLICATIONS J. W. Mellors A Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. 11, 1931 Ed., pages 746-749, Longmans, Green and Co., New York.

I-l. Remy, Vol. 2, 1955 Ed., Treatise on Inorganic,

Chemistry, page 176, Elsevier Publishing Co., New York.

Nature, No. 4146, Apr. 16, 1949, pages 601 and 602, (Vol. 163).

Zeitschrift Fur Anorganische und Allgemeine Chemie, Band 316, (1962), pages '168, 169.

Primary ExaminerEdward Stern Attorney, Agent, or Firm-George L. Church; Donald Johnson; Dr. Paul Lipsitz [57] ABSTRACT 3 Claims, N0 Drawings MANUFACTURE OF HYDROGEN As is well known, hydrogen is an important industrial gas and is becoming, of greater importance as a non-polluting source of energy. Accordingly, it is important that new and economical methods be found for the manufacture of this important energy source. An obvious choice as source of hydrogen is water or steam and numerous processes already exist for the conversion of steam to hydrogen. The best known of such processes is the steam'methane process which has enjoyed industrial success. However, the steam-methane process suffers from certain disadvantages, not the least of which is the short supply and relatively high cost of methane. Since hydrogen will be required in very large amounts for upgrading coal and oil shale to liquids and gases it is most desirable that new improved hydrogen processes be developed using minimum cost fuels such as coal, residual oils, and the like.

It is disclosedin US. Pat. No. 2,042,285 (Wilke et al, issued May 26, 1936) that methane may be converted to a mixture of carbon monoxide and hydrogen by passing a gaseous substance containing methane at 600 to llOC. over a higher oxide of a metal such as titanium, chromium, molybdenum and tungsten and it is further disclosed that the resulting lower oxide, which is obtained in the process, may be converted to a higher oxide with the aid of substances supplying oxygen; e.g.,

- air, steam or carbon dioxide whereby nitrogen, hydrogen or carbon monoxide, respectively, are obtained. However, thermodynamic studies of the free energies for the reduction of the common oxides (W0 and W0 with hydrogen and carbon monoxide, and oxidation of these oxides with steam shows that they are not useful in a coupled system for an oxidation-reduction cycle with hydrogen (or carbon monoxide) and steam.

It has now been found that a viable process for manufacturing pure hydrogen is achieved by contacting a particular tungsten dioxide namely W0 with steam at a temperature below about 700C, preferably between about 400 and 650C. to produce hydrogen product and W.,O andregenerating the starting W0 from the W 0 by contacting the W 0 with a reducing gas at a temperature between 725C. and about 775C., preferably about 750C. whereby the newly found W0 may be oxidized with steam to give hydrogen and the cycle thus repeated. 7

As indicated, hydrogen is generated by reacting steam with W0 However, in starting up the process, the reactor is conveniently charged with W0 which is converted to W0 by passing hydrogen gas over itat a temperature of about700 to about 750C. For the process reaction, the tungsten dioxide in the reactor is preferably maintainedin a fixed, moving or fluidized bed held'ata temperature between 400 and 650C.,

The reducing gas that is passed over the W0 is preferably obtained from a carbonaceous fuel which 'is burned in air and steam at about 1 100C. and is preferably producer gas which is an economical source of hydrogen and CO. Such a gas will contain hydrogen and carbon monoxide and on contacting the W 0 will be converted to water and carbon dioxide respectively, the tungsten oxide product being W0 The W0; is then allowed to cool and is again used for reaction with steam at 400 to 650C. as explained above'whereby additional hydrogen is produced.

As indicated, the preferred reducing gas for use in a the process is a producer gas which is readily available from various sources in refinery operations and is made by blowing a mixture of air or oxygen and steam through a bed of incandescent carbonaceous fuel and its composition will vary depending upon the source of fuel and equipment used in making the gas (see Cost Engineering, July 1963, pages 41 1 Typically, commercial producer gas from coke made with oxygen (not air) contains on a percent by volume basis about 53% CO and about 31% hydrogen.

In order to further illustrate the invention, the following examples are given:

EXAMPLE 1 grams of tungstic trioxide (W0 are placed into a ceramic tube which is electricallyheated to 750C. and hydrogen is passed over the tungsten oxide for one hour to reduce it to W0 The reactor is then cooled to 600C. and steam is introduced into the tube. The effluent vapor is passed through a condenser and the gaseous hydrogen product is collected by displacement of water. A total of 5.4 liters of hydrogen is thereby collected. v

The W 0 oxide now in the reactoris reduced with hydrogen at 750C. to obtain W0 Treatment of the W0 with, steam at 600C. again gives 5.3 liters of hydrogen.

EXAMPLE [1 Carbon monoxide is passed over the same charge of tungsten oxide used in Example I which after the steam EXAMPLE Ill The ceramic reactor is chargedwith l 15 grams l-larshaw W-010ltungsten'catalyst (10% W0 on A1 0 This is alternately reduced to W0 at 750C. with either H and CO and then cooled to 650C. for oxidation with steam to give the following results:

Yield H From Cycle Reducing Gas the. Steam Reaction l H, 910 cc ll H; 820 cc [1! C0 740 cc lV C0 760 cc As pointed out above, thermodynamic studies show that insofar as tungsten oxides are concerned, only the WO W O couple can be ,used for hydrogen manufacture in accord with the system of the above examples. Furthermore, even for this system to obtain maximum use of the hydrogen and carbon monoxide, the reduction of the W must be carried outin the relatively narrow temperature range of from about 725 to 775C., preferably about 750C. On the other hand, in order for the oxidation of W0 by steam to occur favorably, the temperature-must be below 700C., preferably 400 to 650C, preferably about 600C.

An attempt to use a W0 system where W0; is reduced to metal with hydrogen'will require a temperabecause the steam reaction with W 0 is not thermodynamically favored. Thus, the operation of applicants process is dependent upon the specific WO -W O system as described above.

The invention claimed is:

l. A process for the manufacture of hydrogen which comprises contacting tungsten dioxide with steam at a 7 temperature below about 700C. to produce hydrogen and W 0 regenerating tungsten dioxide from said W 0 by contacting said W 0 with a reducing gas at a temperature between about 725C. and 775C., and again contacting the tungsten dioxide formed with steam in a new cycle to generate hydrogen.

2. the process of claim 1 where the steamreaction is carried out at about 600C. and the reduction of W 0 is carried out at about 750C.

3. The process of claim 2 where the reducinggas is producer gas. a r 

1. A PROCESS FOR THE MANUFACTURE OF HYDROGEN WHICH COMPRISES CONTACTING TUNGSTEN DIOXIDE WITH STEAM AT A TEMPERATURE BELOW ABOUT 700*C, TO PRODUCE HYDROGEN AND W4011, REGENERATING TUNGSTEN DIOXIDE FROM SAID W4011 BY CONTACTING SAID W4O11 WITH A REDUCING GAS AT A TEMPERATURE BETWEEN ABOUT 725*C AND 775*C., AND AGAIN CONTACTING THE TUNGSTEN DIOXIDE FORMED WITH STEAM IN A NEW CYCLE TO GENERATE HYDROGEN.
 2. the process of claim 1 where the steam reaction is carried out at about 600*C. and the reduction of W4O11 is carried out at about 750*C.
 3. The process of claim 2 where the reducing gas is producer gas. 